Fibrous wall board



Patented Apr. 15, 1930 UNITED" STATES PATE'NT- OFFICE HARRY E. BROOKBY, OF EVANSTON, ILLINOIS, ASSIGNOR TO UNITED STATES G YP- SUM COMPANY, 01! CHICAGO, ILLINOIS, A. CORPORATION OF ILLINOIS rnmotrs WALL BOARD No Drawing. Application filed February This invention relates to building materials, but more particularly to a material to be used as a lumber substitute, and the process for making such a material.

It is the object of this invention to manufacture a lumber substitute material from cornstalks with the incorporation of peat.

Peat is a material of various properties resulting from disintegration of vegetable matter, great quantities of which are available in natureat a very low price. There are also available, in various sections of the world, great quantities of an agricultural waste, resulting from crop material, maize, or lndian corn. As is well known, this material is capable of producing high-grade fibers of great length and strength. It has been found that by producing fibers from maize stock and commingling 2o them with peat under material can be produced which has very desirable properties when used in such materials as wallboard, building board, thermal insulating board, and similar materials.

Peat has been used heretofore in the manufacture of paper and other fabric materials, but these have never been commercially successful, except where very fibrous peat has been used. This invention, however, renders available all grades of peat for use in this purpose. Cornstalk fiber properly manipulated has the peculiar properties which make a pulp free draining, and canbe used with large quantities of peat. This is especially advantageous because it permits the use of short fiber peat which has previously been unusable and unserviceable.

Inpracticing my invention, I take cornstalks, including leaves, tassels and the roots, if cleaned from dirt and refuse, and if very dry, dampen slightly to keep down dusting in the shredding operation. Thecornstalks are shredded through a hammer mill to rather fine uniform shreds. Thisshredded stock goes to a paper stock beating engine and during the beating I prefer to add fresh water continuously and siphon off an amount equal to this added quantity to remove the pith as it loosens from the stalks during the beating. The pipe withdrawing this water containing high tensile proper conditions, a.

5, 1927. Serial No. 166,274.

pith is covered with a coarse screen to hold ack the stock and the efliuent is screened through a -80 mesh screen to catch the fine fibers and the pith. With this process of beating, the beater stock is freely dewatered after forming-into sheet on the machine.

The separated pith preferably but not necessarily is digested several hours with a suitable alkaline chemical solution, such as a 2-5% N aOI-l solution, or its equivalent from lime and soda ash. 1-4 hours digestion at 40 lbs/in. pressure is suflicient for practical purposes. However, it can be utilized hack in the beater stock direct without digestion without detrimental efiects, for it is the removal of the pith that primarily assists in the beating engine better preparing the corn- .stalks fibers. The digested pith is mixed with the peat which is being prepared simultaneously in a separate beating engine and this beating engine serves largely as a mixer and is not operated to give much fiber reduction or to permit much gelatinization ofthe eat. P When both the cornstalks and the pith, peat stock are sufiiciently prepared, they are mixed together in the desired proportions for the particular character of the finished product, and given a light Jordan action before proceeding to the forming machine. In practice I have found that 50 parts of cornstalk pulp, 50 parts of peat and pith mixture, the pith being that supplied by the cornstalks, give asatisfactory board, but as much as 90% cornstalks and 10% peat may be used if desired. k

' The board sheet may be formed in several laminations wet, over multiple cylinder moulds, oron travelling screens and further 1 willdetermine the thickqlillel'lt pressing operations and reduction; in I t ickness necessary for the final sheet. Insulation properties of course, demand a lighte weight sheet, and one which must be less dense than ordinary wallboard and building boards requiring higher strength and greater density. Whether laminated or formed in one sheet, the formed board sheet is too thick to be advanced from the forming process, except in a substantially horizontal plane and thus it continues on" this horizontal plane through the dry kiln, as one continuous board, being held in place on the advancing dryer deck by superimposed rollers, such as practiced generally in the standard commercial fabrication and drying of these thicker fibre boards. I do not claim as a specific merit of my process any particular forming, fabricating, and drying machine assembly, as the particular object of my invention is to so prepare the raw fibrous stocks, that they can be manipulated on any standard method now well established in forming such fibrous boards, pressing them, drying them, and finally repressing to secure the desired finished di1ne11- sion necessary for the particular use intended. By my process I render these cheap raw materials available for such board manufacture. These have not hitherto been rendered available because of the difficulties in dewatering the sheets with the substantial peat content, and also the low strength that such boards, when attempted in the past, usually had.

In my. process thecornstalks supply the fiber matrix while the peat is a plastic which fills in between the fibers. Ordinarily boards made from these mixed stalks do not require any sizing addition, since the peat naturally contains waxy material having some sizing efi'ect. But resin size precipitated by alum as in the ordinary practice of the paper and fiber board industry can be used to improve the moisture resisting properties of the board, if desired.

Thus, in my process with the cornstalks as furnishing the coarse long fiber matrix,

while the peat (and accumulated pith) is the plastic material which fills out this matrix and gives a body to the board, a wide range in finished products is possible. The percentage of fiber can be varied in wide limits and also the percentage of the plastic can be varied in wide limits, so the boards can be made very open and porous, or can be made very dense and smooth. As examples, I have found that finished board consisting of 50 parts cornstalk material, 50 parts peat at .41 thickness weighs approximately 1100 a thermal conductivity for 1 inch of thickness, expressed in the usual terms, of .6 B. t. u. per hour.

Having thus described my invention, I

a mixture of comminuted cornstalk fibers and fibrous peat.

3. A fibrous building material comprising a mixture of 90% comminuted cornstalk fibers and 10% peat. v

4. A fibrous building material comprising a mixture of comminuted cornstalk fibers and peat, with a water repelling agent, such as saponified rosin and alum.

5. A process of manufacturing a fibrous building material from cornstalks and peat by first shredding the cornstalks, reducing the pulp to a suflicient degree of fineness, adding a quantity of peat, then pulping the mixture until the peat is sufliciently mixed and pulped, forming into a fibrous mass by removing a portion of the water, pressing the mass, and drying.

6. A process of manufacturing a fibrous material from cornstalks and peat, which includes first shredding the cornstalks, pulping said cornstalks until sufficiently fine, adding -a quantity of peat, pulping the mixture until the peat is sufiiciently mixed and pulped, forming said mixture into a fibrous sheet by removing a portion of the water, pressing the sheets into composite board form, and dr ing the pressed sheets.

. The process of manufacturing a fibrous material from cornstalks and peat by first shredding the cornstalks, cooking the stalks under an elevated pressure with a solution containing a chemical. which will soften and. hydrate the fibres, pulping the cornstalks until sufiiciently fine,=.adding a quantity of peat and pulping the mixture until it is intimately mixed and pulped, forming a fibrous mass by removing a portion of the Water, pressing the mass, dryingfi and ire-pressing.

HARRY BROOKBY.

pounds per 1,000 square feet. Such board has 

